linux-kernel - [PATCH 2/2] usb: gadget: udc: Update USB gadget state during soft disconnect

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Message-ID: <20250301003452.2675360-3-quic_wcheng@quicinc.com>
Date: Fri, 28 Feb 2025 16:34:52 -0800
From: Wesley Cheng <quic_wcheng@...cinc.com>
To: <gregkh@...uxfoundation.org>, <Thinh.Nguyen@...opsys.com>
CC: <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        Wesley Cheng
	<quic_wcheng@...cinc.com>
Subject: [PATCH 2/2] usb: gadget: udc: Update USB gadget state during soft disconnect

In the soft disconnect scenarios, the USB connection will be lost
momentarily, so the proper gadget state should be reflected during the time
the connection is unavailable.  Add a flush_work() call, to ensure that
gadget->work is completed before continuing with the UDC unbind sequence.
Since usb_gadget_set_state() queues work to a workqueue, depending on when
the queue is scheduled, this avoids a possible use after freed scenario as
the USB gadget will most likely be freed shortly after the UDC driver is
unbounded.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/gadget/udc/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 4b3d5075621a..7e401cb5a265 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -775,8 +775,10 @@ static int usb_gadget_disconnect_locked(struct usb_gadget *gadget)
 	}
 
 	ret = gadget->ops->pullup(gadget, 0);
-	if (!ret)
+	if (!ret) {
 		gadget->connected = 0;
+		usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
+	}
 
 	mutex_lock(&udc_lock);
 	if (gadget->udc->driver)
@@ -1669,6 +1671,7 @@ static void gadget_unbind_driver(struct device *dev)
 		synchronize_irq(gadget->irq);
 	mutex_unlock(&udc->connect_lock);
 
+	flush_work(&gadget->work);
 	udc->driver->unbind(gadget);
 
 	mutex_lock(&udc->connect_lock);